1. Field of the Invention
The present invention relates to an improved membrane separation process for making enhanced flavor fluids, and particularly, enhanced flavor low-alcohol brews.
2. Related Background Art
There is potentially a very large and profitable market for non-alcohol beer beverages, or non-alcohol brews. Most states define "beer" or "wine", as containing one-half of one percent or more of alcohol by volume. Accordingly, to qualify for the designation as "non-alcohol", the beverage must have an alcohol content of less than 0.5% by volume. Because of the very low alcohol content, "non-alcohol", beverages are not subject to an alcohol tax, yet can be sold at prices comparable to that of regular beers that have ethanol concentrations of about 3.0% to 5.0% by volume. Despite the potential growth market, current non-alcohol brews have not become popular because they lack the full flavor of regular beers.
The chemical composition of the flavor components of any given type of beer is very complex, and may include many chemical compounds. Sometimes, important flavor components are present in only trace amounts. However, the major flavor components, that is those contributing to the aroma and/or taste of beer, include alcohols and esters. Regular beers contain about 4% ethanol, by volume, and lower levels of higher alcohols, such as propanol and isobutyl alcohol. The major flavor components are esters, such as ethyl acetate, amyl acetate, phenyl acetate and the like.
Evaporation and dialysis are processes currently used to prepare non-alcohol brews. Both of these processes operate by removing the undesirable alcohol, ethanol, from regular beer. Unfortunately for consumers, these processes also remove key flavor components during the processing and produce non-alcohol brews with poor flavor profiles, that is taste and aroma profiles. The evaporation process either destroys or causes the loss of heat-labile and highly volatile flavor components. Dialysis is a membrane separation technique that is generally not selective enough to separate ethanol from the beer without also extracting other low molecular weight flavor components. Table 1 lists the concentration, in parts-per-million (ppm), of selected compounds comprising the flavor components of commercially available beers: O'Doulls.RTM., a commercially treated non-alcohol brew, Michelob Pale Ale.RTM., a specialty, high-flavor beer, and Budweiser.RTM., a regular, full-flavor, beer, each sold by the Anheuser-Bush Co.,
TABLE 1 __________________________________________________________________________ Old Compound Michelob Milwaukee .RTM. (ppm) O'Doul's .RTM. Pale Ale .RTM. Budweiser .RTM. NA Sharps .RTM. Coors .RTM. NA __________________________________________________________________________ ethyl acetate 0.7 44.0 23.0 -- -- 5.9 isoamyl acetate 0.1 3.2 2.1 -- -- -- amyl alcohol 8.6 78.0 71.0 7.8 4.6 5.0 isobutyl 1.4 34.0 10.0 2.1 2.05 1.9 alcohol propanol 1.3 38.0 14.0 1.3 1.1 16.3 ethanol* 0.3 5.2 5.1 0.4 0.36 0.48 __________________________________________________________________________ *Ethanol concentration is % by volume NA Nonalcohol brew
Inc., St. Louis, Mo., and non-alcohol brews Old Milwaukee.RTM., sold by the Stroh Brewery Company, Detroit, Michigan, Sharps.RTM., sold by Miller Brewing Company, Milwaukee, Wisconsin, and Coors.RTM., sold by Coors Brewing Company, Golden, Colo. The non-alcohol brews lack, or contain very low concentrations of important beer flavor components, as compared to a high-flavor or full-flavor beer.
Membranes may be used to transport solubilized substances from a concentrated solution, often called a "feed" solution, through the membrane, to a fluid containing little or none of the substances. This fluid is often referred to as a "pick-up" fluid or permeate, because this fluid picks up the components from the feed solution by permeation through the membrane. The membranes may be used to selectively transport these substances from a feed solution to a pick-up fluid based on differences between the rate of transport of different substances across the membrane.
Many different types of membrane separation systems are well known in the art and are described in Membrane Separation Systems--A Research and Development Needs Assessment, Vol. II, Chapt. 1, by R. W. Baker, prepared by the U.S. Department of Energy, Final Report: April, 1990.
Improved ethanol extraction membranes have been developed. For example, Maston, U.S. Pat. No. 4,816,407, discloses use of a semi-permeable membrane for extracting ethanol from an alcohol-containing composition. However, it would be useful to develop flavor component extracting processes to provide a flavor extract that could be used to reconstitute or enhance the flavor profile of the present non-alcohol brews.
The process of pervaporation has been applied to the extraction of aroma components in wine. D. Beaumelle, et al., Journal of Food Engineering, 16 (1992) 293-307. Pervaporation is a separation process used to fractionate liquid mixtures to transport organic aroma components through a membrane to a permeate followed by evaporation of the permeate and the recovery of the aroma faction. The recovered aroma fraction may be used to restore the flavor of non-alcohol wine. A major disadvantage of this process is the required evaporation of the permeate. The concentration of highly volatile aroma components in the aroma fraction may be reduced as a result of this treatment, thereby reducing the quality of the "aroma" added back to the non-alcohol wine.
Accordingly, it would be advantageous to develop a selective separation process that could provide enhanced separation between flavor components and alcohol and produce enhanced flavor fluids, particularly low-alcohol brews, having the complete spectrum of the taste and aroma components extracted in the separation process.